package com.gkcx.demo;

import java.util.Random;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class ReadWriteLockTest {
    public static void main(String[] args) {
        final Queue3 q3 = new Queue3();
        for(int i=0;i<3;i++)
        {
            new Thread(){
                public void run(){
                    while(true){
                        q3.get();
                    }
                }

            }.start();
        }
        for(int i=0;i<3;i++)
        {
            new Thread(){
                public void run(){
                    while(true){
                        q3.put(new Random().nextInt(10000));
                    }
                }

            }.start();
        }
    }
}

class Queue3{
    private Object data = null;//共享数据，只能有一个线程能写该数据，但可以有多个线程同时读该数据。
    private ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
    public void get(){
        rwl.readLock().lock();//上读锁，其他线程只能读不能写
        System.out.println(Thread.currentThread().getName() + " be ready to read data!");
        try {
            Thread.sleep((long)(Math.random()*1000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName() + "have read data :" + data);
        /*rwl.writeLock().lock();
        rwl.writeLock().unlock();*/
        rwl.readLock().unlock(); //释放读锁，最好放在finnaly里面
    }

    public void put(Object data){

        rwl.writeLock().lock();//上写锁，不允许其他线程读也不允许写
        System.out.println(Thread.currentThread().getName() + " be ready to write data!");
        try {
            Thread.sleep((long)(Math.random()*1000));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        this.data = data;
        System.out.println(Thread.currentThread().getName() + " have write data: " + data);
       /* rwl.readLock().lock();
        rwl.readLock().unlock();*/
        rwl.writeLock().unlock();//释放写锁
    }
}
